Fixing the clang fetchsvn hash. I don't know why it does not match that given by nix-prefetch-svn, but
I set that given by nix-build.
svn path=/nixpkgs/trunk/; revision=22239
If passing to gcc4.5 the compile flag: "-fplugin=dragonegg.so" it will use the llvm optimizers and
code generators.
In that previous commit I enabled link time optimization and plugin support in gcc 4.5.0
svn path=/nixpkgs/trunk/; revision=22235